Stabilizing effects of Ag doping on structure and thermal stability of FeN thin films

In this work, we investigated the effect of Ag doping (2-20 at.%) on the phase formation of iron mononitride (FeN) thin films. Together with deposition of FeN using reactive dc magnetron sputtering, Ag was also co-sputtered at various doping levels between 2-20 at.%. We found that doping of Ag around 5 at.% is optimum to not only improve the thermal stability of FeN but also to reduce intrinsic defects that are invariably present in (even in epitaxial) FeN. Conversion electron Mössbauer spectroscopy and N K-edge x-ray near edge absorption measurements clearly reveal a reduction of defects in Ag doped FeN samples. Moreover, Fe self-diffusion measurements carried out using secondary ion mass spectroscopy depth-profiling and polarized neutron reflectivity in 57Fe enriched samples exhibit an appreciable reduction in Fe self-diffusion in Ag doped FeN samples. Ag being immiscible with Fe and non-reactive with N, occupies grain-boundary positions as nanoparticles and prohibits the fast Fe self-diffusion in FeN.

Fabrication of cellulose-based aerogel for thermal and acoustic insulation applications

A method to prepare aerogels from rice straw and polyvinyl alcohol in the presence of fiberglass and glutaraldehyde is herein reported. The morphology, pore structure and physical properties of the aerogels were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), thermal conductivity, water contact angle (WCA) measurements, oil adsorption and sound absorption measurements. The obtained aerogels should be considered as a promising material for upcoming applications, since it has high porosity (up to 93.72%), low density (0.083-0.127 g/cm3), super low thermal conductivity (0.032-0.048 W/mK), high Young modulus (0.201-1.207 MPa), high sound absorption (absorption coefficient of 0.87) and a good oil adsorption capacity (4.8 g/g).

MULTICHARME: A modified Chernin-type multi-pass cell designed for IR and THz long-path absorption measurements in the CHARME atmospheric simulation chamber

We have developed MULTICHARME, a modified Chernin-type multi-pass cell especially designed for IR and THz long-path absorption measurements in the CHamber for Atmospheric Reactivity and Metrology of the Environment (CHARME). By measuring the output power using a near-IR diode-laser and a THz amplified multiplication chain, we have established that the effective reflectivity of MULTICHARME is better than 94 % over approximately three decades of frequency. Absorption measurements of N2O have been performed by probing highly excited rovibrational transitions in the near-IR and ground state rotational transitions at submillimetre wavelengths. In each case the linearity of the absorbance with the pathlengths was verified. Finally, we demonstrate that THz spectroscopy is able to study the isotopic composition of greenhouse polar gases such as N2O and to absolutely quantify stable (N2O) and reactive (O3) species at trace levels. Moreover, a THz monitoring at low pressure of the ozone decay in the chamber has been performed. The deduced ozone lifetime of 3.4 ± 0.1 h is shorter compared with previous measurements performed in CHARME at atmospheric pressure. For the first time, the ability of THz rotational spectroscopy to monitor, with a very high degree of selectivity, stable and reactive polar compounds at trace level in an atmospheric simulation chamber is demonstrated. However, the sensitivity of the THz monitoring needs to be improved to reach the atmospheric trace levels. For this purpose, it is necessary to figure out the baseline variations as well as possible induced by the multiple standing waves present in MULTICHARME.

A Critique on “Measurement of the Hygric Resistance of Concrete Blocks with Perfect Contact Interface: Influence of the Contact Area”

Background: In March 2021, this journal published the article “Measurement of the hygric resistance of concrete blocks with perfect contact interface: influence of the contact area”. That article reports on a study on the impact of ‘perfect contact’ between concrete blocks on moisture absorption, with a focus on the impact of the sample cross-section. Objective: This critique aims at formulating several essential concerns on the hygric aspects of that article, thus expressing the discusser’s reservations on the reliability of the presented outcomes in particular and the published article in general. Methods: The data, as provided in the graphs of the critiqued article, are digitally extracted and further analysed by the discusser. Results: That analysis results in serious concerns with regard to 1) the magnitude of the quantified post-interface flows, 2) the distinguishability of the moisture absorption in the monolithic and perfect contact samples, 3) the robustness of the knee-point identification algorithm, 4) the dependability of the capillary absorption measurements, and 5) the consistency of the capillary absorption processing. These are finally translated into 8 concrete questions to be addressed by the authors of the critiqued article in order to placate these doubts and establish the reliability of their work. Conclusion: This critique formulates appreciable apprehension with respect to an earlier publication in the journal and invites its authors to respond to that via answering the 8 concrete questions. If not satisfactory, then the critiqued article’s findings cannot be considered reliable, and the journal should reconsider its prior publication.